Field of the Invention
The present invention relates to high density memory arrays based on RRAM devices, and particularly relates to a verify scheme for such devices.
Description of Related Art
Resistive random access memory (RRAM) is a type of nonvolatile memory that includes metal oxide material which changes resistance between two or more stable resistance ranges by application of electrical pulses at levels suitable for implementation in integrated circuits. The resistance can be read and written via random access. The access lines coupled to the memory cells are connected to circuitry to perform operations, such as SET and RESET operations, which change the state of the memory element in order to store or erase data.
If the data is not stored successfully, the conventional approach then strengthens the operation conditions, such as greater amplitude and/or longer pulse duration. Such stronger operation conditions, however, stress and damage the memory element, which makes the device less reliable over repeated use.
It is desirable to provide a new verification scheme for RRAMs to reduce stress and damage to the memory element.